Food compositions including resistant starch

ABSTRACT

The invention described in this application relates to food compositions such as breakfast cereals, bread and the like which have an enhanced dietary fibre content. In each case the source of dietary fibre is a starch, preferably a maize starch, having an amylose content of 50% or more, the starch being incorporated into a food composition as appropriate. Alternatively, grains or legumes or parts thereof which include starch of this amylose content may be used.

TECHNICAL FIELD

[0001] This invention relates to food composition which includeresistant starch as a source of dietary fibre and in particular to foodcompositions which include grain or parts thereof and starch derivedfrom the grain which is high in amylose.

BACKGROUND ART

[0002] It has been recognised that a balanced diet must include anadequate level of dietary fibre. There are many natural food sources ofdietary fibre of which cereals, particularly bran, are recognized as agood source.

[0003] However, it would seem that a high proportion of diets of peopleof the developed countries contain an inadequate level of dietary fibre.An inadequate level of dietary fibre has been linked with a number ofdiseases which may be broadly classified as metabolic andgastrointestinal. Examples of these diseases are diabetes mellitus,diverticular disease and colonic cancer.

[0004] It has also be found that some forms of dietary fibre are usefulin lowering blood cholesterol.

[0005] One approach to providing adequate levels of dietary fibre hasbeen to produce processed foods which are high in dietary fibre content.Such foods include breakfast cereals, snack bars, bread and the like.Typically bran, outer tissues of the kernel, including pericarp from avariety of cereal sources including wheat, maize, oats and other plantextracts have been used as the source of fibre.

[0006] More recently, resistant starches have been recognized as apotential source of dietary fibre. Resistant starches are starches thatare highly resistant to hydration and which when ingested pass throughthe upper regions of the gastrointestinal tract largely unchanged.

[0007] To date the only natural sources of resistant starch at asignificant level are green bananas and raw potatoes. Such sources do,however, present substantial problems in formulating satisfactory foodproducts, in particular low gelatinization temperatures which aretypically 60-80° C.

[0008] It is also possible to produce resistant starch by extensiveprocessing involving repeated cooking and cooling of starch pastes.

[0009] In copending International patent application No. PCT/AU93/00389filed Jul. 30, 1993 entitled “High Amylose Starch and Resistant StarchFractions” there is disclosed a hybrid maize seed which is capable ofproducing a starch having an amylose content of more than about 80%.That application further discloses a maize starch derived from such seedhaving a amylose content of more than about 80%. This starch wasdesignated as “High Amylose Starch” in view of the surprising highamylose content. A number of examples of compositions including highamylose starch were given which included a number of food applications.

[0010] Surprisingly, it has now been found that the aforementioned highamylose starch is high in dietary fibre content and is a resistantstarch. Moreover, it has been found that such starches may beadvantageously incorporated into food products to achieve enhancedlevels of dietary fibre content. Additionally, these starches haverelatively high gelatinization temperatures, typically 160-170° C.

SUMMARY OF THE INVENTION

[0011] Accordingly, the present invention consists in a food compositionhaving an enhanced dietary fibre content, characterised in that thedietary fibre is derived from a starch having an amylose content of atleast about 50% or if a rice starch, at least 27% and/or from a grain orparts thereof, the starch content of which has an amylose content of atleast about 50% or if a rice starch, at least about 27%.

DISCLOSURE OF INVENTION

[0012] For the purpose of the description that follows, “high amylose”means an amylose content (dsb;) of 50% or more, preferably 70% or more,most preferably 80% or more. Particularly preferred amylose contents are85% or more and 90% or more. For a rice starch, an amylose content of27% or more is considered to be a “high amylose starch”. Note that themethod used to determined amylose content is that described inapplication No. PCT/AU93/00389, the contents of which are incorporatedherein by way of reference.

[0013] Whilst the resistant nature of the starches of this invention arenot fully understood, it is suspected that the molecular arrangement ofthe glucan polymers, including crystalline structures, and theassociation of these polymers with other substances, including freefatty acids, may be responsible for imparting the resistantcharacteristic.

[0014] In the accompanying FIG. 1, there is shown a graph of totaldietary fibre versus amylose content of a number of samples representingthree maize varieties-regular maize, waxy maize and high amylose maize.It will be seen from this graph that all the regular maize and waxymaize varieties were substantially nil in dietary fibre content, whereasall of the high amylose samples were found to have a measurable dietaryfibre content. Based on the fact that the regular maize samples werefound to have an amylose content of about 28% whilst the waxy maize wasnil, the finding that at an amylose content of greater than about 50%was associated with the presence of dietary fibre is somewhatsurprising. It is also surprising that the dietary fibre contentincreases to such an extent relative to increasing amylose content.

[0015] In Table 1 set out below, it will be seen that when resistantstarch is determined by two methods, the content for the high amylosestarches, particularly high amylose 80, is substantially greater thanregular maize starch. TABLE 1 TOTAL DIETARY FIBRE AND RESISTANT STARCHLEVELS IN MAIZE STARCH Total Insoluble Resistant Starch Dietary FibreMuir et al McCleary et al (% dsb) (% dsb) (% dsb) Waxy Maize <0.2 0.7 ±0.5 5.8 Starch 8/91 Regular Maize <0.2 1.3 ± 0.9 −0.4 Starch 7/91 HighAmylose 50 8.0 8.2 ± 0.4 7.5 7/91 High Amylose 80 21.2 — 11.9 4/91 HighAmylose 80 31.8 20.0 ± 1.8 18.1 10/91

[0016] The high amylose starch of the invention may be incorporated intoa wide range of food products. A non-exhaustive list of such productsinclude: pasta, noodles, instant noodles, breakfast cereals, baked goodssuch as bread, biscuits, crackers and the like, snack foods, cheese andother dairy based products.

[0017] Incorporation of the high amylose starch of the invention intofood products will be at a level consistent with the required level ofdietary fibre in the finished product. A broadly useful level ofincorporation generally lies in the range of from about 5-60%.

[0018] It will be appreciated that in some products, high amylosecontent whole grain or grits derived from the grain may be incorporatedalone or in combination with high amylose starch.

[0019] Furthermore, the high amylose starch of the invention may be usedas a partial replacement for the flour incorporated in products such asbread.

[0020] Whilst the dietary fibre and resistant starch results shownrespectively in FIG. 1 and Table 1 are directed to maize starch, itshould be appreciated that this invention is not so-limited. Forexample, high amylose wheat, high amylose rice, high amylose pea andhigh amylose barley starch may also be utilized in the food compositionsof this invention.

MODES FOR CARRYING OUT THE INVENTION

[0021] In order to better understand the nature of this invention, anumber of examples will now be described.

[0022] Breakfast Cereals

[0023] The high amylose starch of the invention can be used to advantagein a variety of ready-to-eat breakfast cereals. These include flakedcereals, extruded flake cereals, extruded gun-puffed cereals, extrudedand other shredded cereals, oven-puffed cereals, granola cereals andextruded expanded cereals.

[0024] (1) Flaked Cereals

[0025] While still in grit form A-958 (Hi-maize—high amylose starch 80%,available from Starch Australasia Limited) can be processed to make acornflake by using higher than conventional levels of water addition andlonger cooking times. The final toasted product (formulation 2571/1) hasa light colour and is significantly higher in dietary fibre content asis shown in Table 2.

[0026] (2) Extruded Flake

[0027] An extruded flake product was made by rotary cooking, cold formpelleting, flaking and toasting according to formulation 2562/1. It willbe seen from Table 2 that 2562/1 had a significantly higher dietaryfibre content as compared with the control. Formulation: Extruded Flake2562/1 Control % % Maize Polenta 45.0 45.0 Starch A958 42.0 — RegularMaize Starch — 42.0 Sugar 8.7 8.7 Salt 1.9 1.9 Malt 2.5 2.5 100.0 100.0

[0028] Formulations 2459/2(b) and 2459/2(c) were prepared as 2562/1.However, 2459/2(b) were tempered overnight while for 2459/2(c), theflakes were dried out at 70° C. for 30 minutes prior to flaking.Formulation: Extruded Flake (Multigrain) 2459/2(b) 2459/2(c) % % StarchA958 43.1 43.1 Rice 11.5 11.5 Oats 11.5 11.5 Wheat 20.7 20.7 Sugar 8.68.6 Malt 2.6 2.6 Salt 2.0 2.0 100.0 100.0

[0029] The textural properties of the resultant flakes weresignificantly different for each formulation with the 2450/2 forminghollow or pillow-like flakes, whereas 2459/2(c) had a wrinkled,blistered appearance.

[0030] The dietary fibre content of the two flake formulations 2459/2(b)and 2459/2(c) are set out in Table 2, from which it will be seen thatovernight tempering of the moist pellet containing starch A958 increasesthe total dietary fibre content of the resultant flake significantly. Afurther extruded flake product was made according to formulation 2556/1.Formulation: Extruded Flake 2556/1 % Wholegrain Calrose Rice 56.0Wheatgerm 7.0 Sugar 6.9 Salt 1.5 Malt 1.3 Icing Sugar Mixture 6.3 Gluten12.6 Starch A958 8.4 100.0

[0031] The dietary fibre content for 2446/1 is set out in Table 2. TABLE2 Dietary Fibre Content of Breakfast Cereals Total Soluble InsolubleMoisture Dietary Dietary Dietary Content Fibre Fibre Fibre Formulation %(% dsb) (% dsb) (% dsb) Cornflake 4.6 4.0 1.0 2.9 (Control) 2571/1 6.220.7 1.2 19.5 2562/1 4.7 12.4 0.4 12.0 Control 6.5 3.9 0.3 3.5 2459/2(b)4.3 17.1 — — 2459/2(c) 5.0 15.3 — — 2556/1 5.4 4.5 1.1 3.5

[0032] (3) Wheat Bites

[0033] This product is a crunchy “pillow” which can be consumed as aready-to-eat cereal with milk or eaten piece-wise as a snack.

[0034] The formulation of the product is as follows: Ingredient % (wetmix) Fine wholemeal flour 36.67 Castor sugar 15.35 Oat flour 12.80Starch A958 11.94 Fine Bran #3 8.53 Vitamin B1 0.0051 Vitamin B2 0.0043Niacin 0.0316 Iron 0.0145 Honey 1.19 Water 13.47 100.00

[0035] Preparation of the product is as follows:

[0036] (a) premix dry ingredients;

[0037] (b) process cereal mix with honey and water in a twin screwextruder;

[0038] (c) crimp and cut ropes from extruder to form individual pillows;

[0039] (d) toast pillows to reduce moisture and develop colour andflavour.

[0040] The product-was found to have excellent crunch after contact withmilk for five minutes. It has a distinctive appearance being a pillowwith “strand” markings. Total dietary fibre content was found to be 10%,at a moisture content of 2-4%. The product is unusual in that it has alight airy texture with a relatively high level of total dietary fibre.

[0041] The cereal products described above were characterized by severalphysical properties which were quite unexpected. For example, some ofthe flakes were blistered whilst others were bubbled and appeared as if“popped”. These characteristics are highly desirable and would not havebeen considered achievable using formulations of this type.

[0042] In addition, these cereal products extrude well, display moderateto high expansion, yielding a final product with a medium to coarse cellstructure. The products are unusual in that they have a light airytexture whilst containing a relatively high level of total dietaryfibre.

[0043] The breakfast cereal products have also been found to have anexcellent “bowl life” in that the flakes retained their crunch aftercontact with milk for five minutes.

[0044] Furthermore, during processing and prior to toasting, it wasobserved that the flakes had a tendency to stick less to each other ascompared with the control.

[0045] Bread

[0046] A number of bread samples were prepared using a high amylosestarch and for comparison a waxy maize starch “MAZACA” trade mark ofStarch Australasia Limited. The starches were incorporated into thebread at a 5% and a 10% level of flour replacement.

[0047] In Table 2, set out below, are the results obtained for each ofthe bread samples. These results clearly show that at both the 5% and10% levels of high amylose starch, the dietary fibre content wassubstantially more than both the control product and the mazaca basedproduct. Furthermore, it should be noted that the actual level ofdietary fibre found was significantly more than would be expected. Thissuggests that a synergistic effect occurred during baking.

[0048] Indeed, it would have been expected that the dietary fibrecontent would decrease as resistant starch is destroyed during suchheating processes. TABLE 3 Wheat High Starch Amylose Analysis ControlStarch Mazaca Moisture % — 13.0 12.6 Total dietary fibre — 27 0 (TDF) %(DB) (Resistant starch) Test baking Rate of flour 0 5 10 5 10 5 10replacement (%) Water absorption (%) — — — 58 58 58 58 Total loaf score(%) 76 80 76 75 73 79 71 Fibre in bread TDF % (DB) 4.2 4.0 — 6.9 8.7 4.0(approx. expected — — — 5.2 6.4 4.0 *TDF %)

[0049] A further series of test bakings were done according to theformulations set out below: Batch Nos. Ingredients 1 2 3 4 5 6 Flour (g)1000 950 900 850 800 750 Starch A.958 (g) 0 50 100 150 200 250 Gluten(g) 0 10 20 30 40 50 Salt (g) 18 18 18 18 18 18 Improver (g) 15 15 15 1515 15 Fat (g) 20 20 20 20 20 20 Yeast (g) 12 12 12 12 12 12 Water (mL)600 610 630 650 670 700

[0050] Each batch was processed in a conventional manner. The totaldietary fibre for each batch was found to be: Total Dietary Fibre BatchNo. (% dsb) 1 5.4 2 7.1 3 9.1 4 10.8 5 12.8 6 14.5

[0051] In addition, it was noted that inclusion of the high amylosestarch did not have an adverse effect on crumb colour, whilst increasinglevels of high amylose starch led to increasing dough water absorptionlevels.

[0052] Generally it was concluded that the high amylose starch was anexcellent source of dietary fibre for inclusion in bread since anydetrimental effect on load volume and crumb firmness could be readilyovercome by appropriate formulation changes known to those skilled inthe art.

[0053] It has also been found that gluten free bread which is high indietary fibre may be produced using the high amylose starch of theinvention. This is important as conventional gluten free bread, which isconsumed by sufferers of coeliac disease, is generally low in dietaryfibre.

[0054] For guidance, up to about 15% may be incorporated into a glutenfree bread to yield a dietary fibre content of about 10%.

[0055] As well as being able to provide enhanced dietary fibre contentin bread, the high amylose starch acts to reduce staling on storage ofthe bread, by it is thought, reducing the level of amylopectin andhelping to maintain the moisture content of the bread.

[0056] Noodles

[0057] Typically, up to about 24% of high amylose starch may be used asa flour replacement in spaghetti. This yields a dietary fibre content ofup to about 8.7%.

[0058] In use, it has been found that spaghetti made from high amylosestarch has less of the “speckiness” which is usually associated with theaddition of more conventional fibre additivies such as bran to achievehigher dietary fibre content. Furthermore, during cooking, the spaghettiis less sticky and remains al dente for longer.

[0059] Other Food Products

[0060] It has been found that, in addition to providing a dietary fibrebenefit in instant noodles, these products have a greater crispiness ascompared with conventional formulated products.

[0061] In the formulation of biscuits and crackers, it is possible toovercome the use of a laminator by using the high amylose starch of theinvention. This is due to the expansion, popping effect which serves toimpart a lighter texture to such products.

[0062] Industrial Applicability

[0063] From the foregoing description it will be evident that thepresent invention provides a means for enhancing the dietary fibrecontent of a variety of food compositions. Not only does this haveobvious nutritional benefits, but it allows for the production of foodcompositions having physical characteristics not previously known withconventional formulations.

[0064] It will be appreciated by persons skilled in the art thatnumerous variations and/or modifications may be made to the invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects as illustrative and notrestrictive.

1. A food composition having an enhanced dietary fibre contentcomprising a dietary fibre containing substantially chemicallyunmodified starch having an amylose content of at least about 50% or ifa rice starch, at least about 27%, and/or from a grain or parts thereof,the starch content of which has an amylose content of at least about 50%or if a rice starch, at least about 27%, the enhanced dietary fibrecontent being derived from said starch.
 2. A food composition as inclaim 1 wherein the amylose content of the starch is 55% or more.
 3. Afood composition as in claim 2 wherein the amylose content of the starchis 70% or more.
 4. A food composition as in claim 3 wherein the amylosecontent of the starch is 80% or more.
 5. A food composition as in claim4 wherein the amylose content of the starch is 85% or more.
 6. A foodcomposition as in claim 5 wherein the amylose content of the starch is90% or more.
 7. A food composition as in any one of claims 1 to 6wherein the starch is a wheat, maize, barley, pea or rice starch and/orthe grain or parts thereof is wheat, maize, barley, pea or rice.
 8. Afood composition as in claim 7 wherein the starch is maize starch and/orthe grain or parts thereof is maize.
 9. A food composition as in any oneof claims 1 to 8 wherein the starch and/or the grain or Darts thereofare included in an amount of from about 5-60% to give a dietary fibrecontent of about 1.5-20%.
 10. A food composition as in any one of claims1 to 9 further comprising from 75 to 95% flour.
 11. A food compositionas in claim 10 wherein the flour content is 75%.
 12. A food compositionas in claim 10 wherein the flour content is 80%.
 13. A food compositionas in claim 10 wherein the flour content is 85%.
 14. A food compositionas in claim 10 wherein the flour content is 90%.
 15. A food compositionas in claim 10 wherein the flour content is 95%.
 16. A food compositionas in claim 9 comprising noodles wherein the starch is in an amount ofup to about 24%.
 17. A food composition as in claim 9 comprising breadwherein the starch is in an amount of from about 5-25%.
 18. A foodcomposition as in claim 17 wherein the bread is gluten free and includesthe starch in an amount up to about 15%.
 19. A food composition as inclaim 9 comprising a breakfast cereal.
 20. A food composition as inclaim 19 wherein the breakfast cereal is selected from the groupconsisting of flaked cereals and extruded flakes.
 21. A food compositionas in claim 20 wherein the breakfast cereal is bubbled, popped orblistered in appearance.
 22. A food composition as in claim 21 whereinthe dietary fibre content is about 4.5% or more.
 23. A food compositionas in claim 22 wherein the dietary fibre content is. about 12.4% ormore.
 24. A food composition as in claim 23 wherein the dietary fibrecontent is about 15.3% or more.
 25. A food composition as in claim 24wherein moist pellets produced during formation of the flakes aretempered overnight, such that the dietary fibre content thereof is about17.5% or more.
 26. A food composition as in claim 23 wherein the dietaryfibre content is about 20.7% or more.
 27. A food composition as in claim21 wherein the breakfast cereal is in the form of “pillows” having alight, airy texture.
 28. A food composition as in claim 27 wherein thebreakfast cereal has a dietary fibre content of about 10%.